Kabul, Afghanistan (CNN) -- Just days after the governor of an northeastern Afghanistan province claimed dozens of civilians were killed in a NATO-led mission targeting insurgents, new allegations of civilian casualties surfaced in a nearby province Thursday.

NATO's International Security Assistance Force is investigating the claims stemming from an operation Thursday morning in the Alah Say district of Kapisa province, the military said in a statement. Armed insurgents were the target, ISAF said.

"We take civilian casualty allegations very seriously; we'll investigate this incident as quickly as possible," said U.S. Army Col. Patrick Hynes, director of ISAF Joint Command Combined Joint Operations Center.

The incident followed a statement Sunday from the governor of Kunar province, who said that 64 people -- including 22 women and 26 young boys -- were killed in a joint operation by ISAF and Afghan security forces over a few days last week.

ISAF said video evidence from the scene indicated 36 armed insurgents were killed.